Time: 20 minutes. This quiz is closed book, closed notes.
Below is a gallery of Q-Q plots. In each plot, the X-axis shows the "reference distribution" values and the Y-axis shows the values of some large batch of numbers. As usual, values along the X axis increase to the right and values along the Y axis increase to the top. The reference distribution is unimodal and symmetric (like the Normal distribution).
Each of problems 0 through 5 is a statement about the batch relative to the reference distribution. List all the Q-Q plots that match each description. There may be zero, one, or more than one answer to each question. Take off ten points for each incorrect answer and take off five points for each missing answer. As an example, the zeroth question is done for you.
0. The batch has (approximately) the same shape as the reference distribution: D, E.
1. The batch is long tailed (platykurtic) in both directions.
2. The batch is short tailed (leptokurtic) in both directions.
3. The batch is positively skewed.
4. The batch has a large number of nondetect values with a common detection limit.
5. The batch has two low outliers.
| A | |
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B |
| C | |
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D |
| E | |
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F |
Mary is computing logarithms to an unusual base. To two decimal places, she knows that log(2) = -0.76, log(3) = -1.20, and log(10) = -2.51.
6. What is log(200)?
7. What is log(5)?
8. What is log(1)?
9. What is log(-2)?
10. (Extra credit) What is the base of Mary's logarithms?
Scoring: The passing score is 95. Incorrect "extra credit" answers will be deducted from your score; correct extra credit answers will add to your score.
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This page was created 10 February 2001.